U.S. patent application number 13/497747 was filed with the patent office on 2012-07-12 for parts welded in a rotationally symmetrical manner.
This patent application is currently assigned to RUIA GLOBAL FASTENERS AG. Invention is credited to Robert Bongartz, Reiner Dorow, Kurt Muller.
Application Number | 20120177437 13/497747 |
Document ID | / |
Family ID | 43413550 |
Filed Date | 2012-07-12 |
United States Patent
Application |
20120177437 |
Kind Code |
A1 |
Bongartz; Robert ; et
al. |
July 12, 2012 |
PARTS WELDED IN A ROTATIONALLY SYMMETRICAL MANNER
Abstract
The invention relates to a part (10) welded in a rotationally
symmetrical manner and comprising two parts (12, 14), which are
connected by a rotationally symmetrical weld (16), wherein a main
loading area (22) occurs in the vicinity of the weld (16), and only
the weld (16) and the surroundings (22) thereof are strengthened by
case hardening in the extreme fiber in such a way that case
strengthening is present there, and a method for producing a part
(10) welded in a rotationally symmetrical manner and comprising two
parts (12, 14) by welding a rotationally symmetrical weld (16)
between the two parts (12, 14), wherein after the parts (12, 14)
are welded, the weld (16) and the surroundings (22) thereof are
case hardened and the hardened zone (16, 22) is quenched
immediately thereafter.
Inventors: |
Bongartz; Robert; (Neuss,
DE) ; Dorow; Reiner; (Koblenz, DE) ; Muller;
Kurt; (Mayen, DE) |
Assignee: |
RUIA GLOBAL FASTENERS AG
Neuss
DE
|
Family ID: |
43413550 |
Appl. No.: |
13/497747 |
Filed: |
September 8, 2010 |
PCT Filed: |
September 8, 2010 |
PCT NO: |
PCT/DE2010/050070 |
371 Date: |
March 22, 2012 |
Current U.S.
Class: |
403/122 ;
148/527 |
Current CPC
Class: |
F16C 11/0609 20130101;
B23P 15/00 20130101; C21D 9/0068 20130101; B23P 2700/11 20130101;
Y10T 403/32631 20150115; C21D 1/06 20130101; C21D 9/50
20130101 |
Class at
Publication: |
403/122 ;
148/527 |
International
Class: |
F16C 11/06 20060101
F16C011/06; B23K 31/02 20060101 B23K031/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2009 |
DE |
10 2009 042 714.7 |
Claims
1-4. (canceled)
5. Ball pin (10) comprising a ball (14) and a shaft (12) which are
connected by a rotationally symmetrical welded seam (16),
characterized in that only the welded seam (16) and its direct
surroundings (22) are strengthened after the welding by edge layer
hardening directly followed by quenching of the zone (16, 22)
treated by the edge layer hardening in the edge fibres in such a
manner that an edge layer strengthening is provided there.
6. Method for producing a ball pin (10) comprising a ball (14) and
a shaft (12) by welding a rotationally symmetrical welded seam (16)
between ball (14) and shaft (12), characterised in that after the
welding of ball (14) and shaft (12), an edge layer hardening of the
welded seam (16) and its surroundings (22) directly followed by
quenching of the hardened zone (16, 22) treated by the edge layer
hardening is accomplished.
Description
TECHNICAL FIELD
[0001] The present invention relates to rotationally symmetrically
welded parts which are predominantly exposed to continuous
alternating bending loads, in particular ball pins comprising a
ball and a shaft which are connected by a welded seam. Such ball
pins are used for various applications, for example, gas pressure
spring buffers or steering systems and require a high stability
since such systems are stressed by continuous alternating bending
during operation. In this case, the transition between ball and
shaft is in particular exposed to extremely high loading.
Accordingly, ball pins must be dimensioned so that they withstand
these loads.
PRIOR ART
[0002] In the prior art it was only known hitherto either to turn
such rotationally symmetrical parts in one piece, which is
extremely expensive to manufacture or to simply weld the parts. A
corresponding welding of ball and shaft to form a ball pin as a
rotationally symmetrical part is known, for example, from DE 856
256. In the latter case, fractures frequently occurred between
shaft and ball.
[0003] It is further known from the prior art to subject components
as a whole to a hardening and/or an edge layer hardening, such as
is presented, for example, in DE 10 2004 053 935 A1.
DESCRIPTION OF THE INVENTION
[0004] Starting from this prior art, it is therefore the object of
the present invention to further develop such a rotationally
symmetrical welded part in such a manner that it has an appreciably
higher strength, in particular a substantially higher flexural
fatigue strength, and therefore a correspondingly higher lifetime,
and to provide a method for producing such a part.
[0005] The present invention proposes for solving this object for
the first time merely to subject the welded seam of the
rotationally symmetrically welded part and optionally its
surroundings to an edge layer hardening although this has
encountered prejudice in the prior art in that the edge layer
hardening of a welded seam is always counterproductive since this
causes an embrittlement of the edge layer of the welded seam which
makes the welded seam brittle under tensile loading.
[0006] In many cases of application, as here in a ball pin, no
tensile loading takes place at all but the lifetime of the part is
limited by its flexural fatigue strength.
[0007] Experiments of the patent applicant have revealed that as a
result of the procedure according to the invention, the flexural
fatigue strength of ball pins, for example, can be increased by
about a decade, i.e. by a factor of 10 although in the view of the
experts, edge layer hardening of a welded seam is rather
disadvantageous on account of the resulting embrittlement.
[0008] According to the invention, this object is solved in a
generic rotationally symmetrically welded part whereby the
principal loading region in the edge fibre is strengthened by
strengthening the welded seam and its surroundings by edge layer
hardening in the edge fibre in such a manner that an edge layer
strengthening by intrinsic compressive stresses is provided
there.
[0009] In this case, it is particularly preferred to produce the
edge layer strengthening by edge layer hardening directly followed
by quenching of the hardened zone.
[0010] The present invention is particularly suitable for producing
ball pins consisting of a ball and a shaft which are connected by a
rotationally symmetrical welded seam. Such ball pins are not
usually subjected to any tensile loadings in which edge layer
hardening could be disadvantageous but their lifetime is
exclusively limited by the flexural fatigue strength. Furthermore,
the method of manufacture according to the invention with edge
layer hardening restricted to the welded seam and its immediate
surroundings makes it possible to preserve the gloss level of the
ball.
[0011] A rotationally symmetrical part according to the invention
can be manufactured, for example, by inductive hardening, laser
hardening or plasma ion hardening.
[0012] A method for producing such a rotationally symmetrically
welded part is also provided according to the invention in which
after welding the individual parts an edge layer hardening of the
welded seam and its surroundings directly followed by quenching of
the hardened zone is accomplished.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention is explained in detail hereinafter
with reference to the exemplary embodiment shown in the drawing in
the form of a ball pin:
[0014] In the figures:
[0015] FIG. 1 shows a ball pin according to the invention from the
side, in a partially cutaway view.
BEST MODE FOR IMPLEMENTING THE INVENTION
[0016] FIG. 1 shows a ball pin 10 according to the invention,
comprising a shaft or pin 12 and a ball 14. The ball pin 10 is
shown from the side and the transition region between shaft 12 and
ball 14 of particular interest here is shown in cutaway view.
[0017] The ball pin 10 according to the invention shown here is
produced by welding ball 14 and shaft 12. The corresponding welded
seam 16 can be seen at the edge in the sectional view. It runs
rotationally symmetrically about the axis of rotation 20 of the
shaft 12.
[0018] The welding of ball and shaft produces a heat influx zone 18
around the welded seam 16, which is characterised by the
interrupted shading in the sectional view and when viewed
three-dimensionally is formed approximately as a lens shape
rotationally symmetrically to the axis of rotation 20 of the shaft
12. As can be seen in the drawing, this has a symmetrical elliptic
shape in cross-section.
[0019] According to the invention, the regions 22 shown blank in
the sectional view are particularly hardened so that the ball pin
according to the invention has optimised hardening zones here.
[0020] According to the invention, by means of a special sequence
of process steps, after the welding process the principal loading
region of the welding zone 22 is hardened in the edge fibre so that
edge layering strengthening of the welded seam 16 and its
surroundings comes about. As a result, an appreciable increase in
the lifetime of the ball pin is achieved according to the
invention, even when this is subjected to very severe vibrational
stress.
[0021] The particularly preferred procedure according to the
invention for producing this strengthening in the principal loading
region of the welding zone 22 takes place as follows:
[0022] The ball 14 is welded onto the pin 12. A rotationally
symmetrical welded seam 16 is produced. An edge layer hardening of
the welding zone 22 is then carried out immediately followed by
quenching of the hardened zone 22. The hardening can be
accomplished, for example, by inductive hardening, laser hardening
or plasma ion hardening.
[0023] In this way, the strength of the welding zone 22 which is
particularly sensitive to notch stresses and crack formation is
appreciably improved. The lifetime of the complete component is
thus substantially improved.
* * * * *